Wavelength division multiplexing and demultiplexing (WDM) techniques play an important role in presently used optical fiber telecommunications systems. WDM techniques allow two or more wavelengths of light to be transmitted simultaneously in the same optical fiber. This significantly increases the information carrying capacity of the optical fiber and also significantly reduces the complexity of networks implemented using optical fibers. For example, using WDM techniques, a two way communications link can be achieved using a single fiber.
Typically, WDM devices may be used to multiplex and demultiplex signals 1550 nm and 1300 nm in the case of a single mode fiber system. An example of such a WDM device is the Single Mode Fused Wavelength Division Multiplexer/Demultiplexer produced by Gould Electronics. In the case of a multimode fiber system, the wavelengths may be different, e.g., 1300 nm and 850 nm. When a WDM device is used as a demultiplexer, a multiplexed signal, comprising two wavelengths such as 1550 nm and 1300 nm, enters the WDM device on an input optical fiber. The signal is demultiplexed and signals at the different wavelengths leave the WDM device on separate output fibers. Thus in the example discussed herein, a signal at 1550 nm leaves the WDM device on a first output fiber and a signal at 1300 nm leaves the WDM device on a second output fiber.
Currently available optical isolators using fused WDM devices provide about -16 dB of isolation between the two demultiplexed wavelengths. This level of isolation is not satisfactory for all fiber optic applications.
In view of the above, it is an object of the present invention to provide a connector incorporating a wavelength selective filter to increase the wavelength sensitivity of fiber optic components such as WDM devices. It is a further object of the invention to use such connectors to provide increased wavelength isolation for WDM devices.